The sustained attack on the AT&T monopoly also effected the development of the radio network. This was because, although radio as a medium of mass communications depended on single point distribution, transmission masts, the creation of national radio networks relied on linking these central transmitters in the first instance by wires. In the United States, this once more involved AT&T. As we have seen, AT&T was one of the radio pioneers and had involved itself in running radio stations until 1926. But that same year a new opportunity opened up.